Extracting the sensor calibration files

Note: I've only tested this on 1871_01XX.dat. Use at your own risk and report any errors.

When using the set files (sensor calibration settings) the colors look much better. I only know how to extract them from the windows bootcamp driver. These are the steps you can follow:

1. Download driver package from https://support.apple.com/kb/DL1837
2. Unzip the package with unzip
3. Extract AppleCamera64.exe by running cd BootCamp/Drivers/Apple/ && unrar x AppleCamera64.exe

You should now have the AppleCamera.sys file which is the driver containing the set files.

4. Run the following commands:

dd bs=1 skip=1663920 count=33060 if=AppleCamera.sys of=9112_01XX.dat
dd bs=1 skip=1644880 count=19040 if=AppleCamera.sys of=1771_01XX.dat
dd bs=1 skip=1606800 count=19040 if=AppleCamera.sys of=1871_01XX.dat
dd bs=1 skip=1625840 count=19040 if=AppleCamera.sys of=1874_01XX.dat

You should now have the four .dat files with the follow md5sum checksums:

a1831db76ebd83e45a016f8c94039406  1771_01XX.dat
017996a51c95c6e11bc62683ad1f356b  1871_01XX.dat
3c3cdc590e628fe3d472472ca4d74357  1874_01XX.dat
479ae9b2b7ab018d63843d777a3886d1  9112_01XX.dat

5. Copy the .dat files into your facetimehd firmware directory (eg. /lib/firmware/facetimehd/)
6. Reload the driver

Check that you don't get the "Direct firmware load for facetimehd..." error.

You should now have correct colors.